.
Things have been working swimmingly in many areas of the plugin, but one particular problem has been tough to solve. I have two components that are trying to read/write to the same memory at the same time, causing Rhino exceptions and crashes.
The conflicts appear to be happening between two components -- one is a "Layer Events Listener" that reports essentially what type of layer event just happened. The other is a "Set Layer Visibility" component that toggles the visibility of a list of layers.
The code:
public class LayerTools_LayerEventsListener : GH_Component { /// <summary> /// Initializes a new instance of the LayerTools_LayerListener class. /// </summary> public LayerTools_LayerEventsListener() : base("Layer Events Listener", "Layer Listener", "Get granular information about the layer events happening in the Rhino document.", "Squirrel", "Layer Tools") { }
/// <summary> /// Registers all the input parameters for this component. /// </summary> protected override void RegisterInputParams(GH_Component.GH_InputParamManager pManager) { pManager.AddBooleanParameter("Active", "A", "Set to true to listen to layer events in the Rhino document.", GH_ParamAccess.item, false); pManager.AddTextParameter("Exclusions", "E", "Provide a list of exclusions to stop reading specific events (Added, Deleted, Moved, Renamed, Locked, Visibility, Color, Active).", GH_ParamAccess.list); pManager[1].Optional = true; }
/// <summary> /// Registers all the output parameters for this component. /// </summary> protected override void RegisterOutputParams(GH_Component.GH_OutputParamManager pManager) { pManager.AddBooleanParameter("Initialized", "I", "Whether the listener changed from passive to active.", GH_ParamAccess.item); pManager.AddTextParameter("Document Name", "doc", "Name of the Rhino document that is changing.", GH_ParamAccess.item); pManager.AddTextParameter("Layer Path", "path", "Path of the modifed layer.", GH_ParamAccess.item); pManager.AddIntegerParameter("Layer Index", "ID", "Index of the modified layer.", GH_ParamAccess.item); pManager.AddIntegerParameter("Sort Index", "SID", "Sort index of the modified layer.", GH_ParamAccess.item); pManager.AddTextParameter("Event Type", "T", "Type of the modification.", GH_ParamAccess.item); pManager.AddBooleanParameter("Added", "A", "If the layer has been added.", GH_ParamAccess.item); pManager.AddBooleanParameter("Deleted", "D", "If the layer has been deleted.", GH_ParamAccess.item); pManager.AddBooleanParameter("Moved", "M", "If the layer has been moved.", GH_ParamAccess.item); pManager.AddBooleanParameter("Renamed", "R", "If the layer has been renamed.", GH_ParamAccess.item); pManager.AddBooleanParameter("Locked", "L", "If the layer locked setting has changed.", GH_ParamAccess.item); pManager.AddBooleanParameter("Visibility", "V", "If the layer's visibility has changed.", GH_ParamAccess.item); pManager.AddBooleanParameter("Color", "C", "If the layer's color has changed.", GH_ParamAccess.item); pManager.AddBooleanParameter("Active", "Act", "If the active layer has changed.", GH_ParamAccess.item); }
/// <summary> /// This is the method that actually does the work. /// </summary> /// <param name="DA">The DA object is used to retrieve from inputs and store in outputs.</param> protected override void SolveInstance(IGH_DataAccess DA) { bool active = false; List<string> exclusions = new List<string>();
DA.GetData(0, ref active); DA.GetDataList(1, exclusions);
RhinoDoc thisDoc = null;
bool initialize = false;
string dName = null; string activePath = null; int layerIndex = -1; int sortIndex = -1; string eventType = null; bool added = false; bool deleted = false; bool moved = false; bool renamed = false; bool locked = false; bool visibility = false; bool color = false; bool current = false;
if (active) { thisDoc = RhinoDoc.ActiveDoc;
initialize = (!previouslyActive) ? true : false;
RhinoDoc.LayerTableEvent -= RhinoDoc_LayerTableEvent; RhinoDoc.LayerTableEvent += RhinoDoc_LayerTableEvent; previouslyActive = true;
} else {
RhinoDoc.LayerTableEvent -= RhinoDoc_LayerTableEvent; previouslyActive = false; }
if (ev != null) { dName = ev.Document.Name; layerIndex = ev.LayerIndex; eventType = ev.EventType.ToString();
if (!exclusions.Contains("Active")) { if (ev.EventType.ToString() == "Current") { // active layer has just been changed current = true; }
}
if (!exclusions.Contains("Moved")) { if (ev.EventType.ToString() == "Sorted") { // active layer has just been changed moved = true; }
}
if (!exclusions.Contains("Added")) { if (ev.EventType.ToString() == "Added") { // layer has just been added activePath = ev.NewState.FullPath; added = true; }
}
if (!exclusions.Contains("Active")) { if (ev.EventType.ToString() == "Deleted") { // layer has just been added
deleted = true; } }
if (ev.EventType.ToString() == "Modified") { // layer has been modified activePath = ev.NewState.FullPath;
//skip sortindex eventType = ev.EventType.ToString();
if (ev.OldState != null && ev.NewState != null) { if (!exclusions.Contains("Locked")) { if (ev.OldState.IsLocked != ev.NewState.IsLocked) locked = true;
} if (!exclusions.Contains("Visibility")) { if (ev.OldState.IsVisible != ev.NewState.IsVisible) visibility = true; }
if (!exclusions.Contains("Moved")) { if (ev.OldState.ParentLayerId != ev.NewState.ParentLayerId) moved = true; }
//if (ev.OldState.SortIndex != ev.NewState.SortIndex) moved = true; if (!exclusions.Contains("Renamed")) { if (ev.OldState.Name != ev.NewState.Name) renamed = true; }
if (!exclusions.Contains("Color")) { if (ev.OldState.Color != ev.NewState.Color) color = true; } }
} }
DA.SetData(0, initialize); DA.SetData(1, dName); DA.SetData(2, activePath); DA.SetData(3, layerIndex); DA.SetData(4, sortIndex); DA.SetData(5, eventType); DA.SetData(6, added); DA.SetData(7, deleted); DA.SetData(8, moved); DA.SetData(9, renamed); DA.SetData(10, locked); DA.SetData(11, visibility); DA.SetData(12, color); DA.SetData(13, current);
}
static bool previouslyActive = false; Rhino.DocObjects.Tables.LayerTableEventArgs ev = null;
void RhinoDoc_LayerTableEvent(object sender, Rhino.DocObjects.Tables.LayerTableEventArgs e) { ev = e;this.ExpireSolution(true); }
And for the layer visibility component:
public LayerTools_SetActiveLayer() : base("Set Active Layer", "SetActiveLayer", "Set the active layer in the Rhino document.", "Squirrel", "Layer Tools") { }
/// <summary> /// Registers all the input parameters for this component. /// </summary> protected override void RegisterInputParams(GH_Component.GH_InputParamManager pManager) { pManager.AddBooleanParameter("Active", "A", "Set to true to change the active layer in Rhino.", GH_ParamAccess.item, false); pManager.AddTextParameter("Path", "P", "Full path of the layer to be activated.", GH_ParamAccess.item); }
/// <summary> /// Registers all the output parameters for this component. /// </summary> protected override void RegisterOutputParams(GH_Component.GH_OutputParamManager pManager) { pManager.AddIntegerParameter("Layer ID", "ID", "Index of layer that has been activated.", GH_ParamAccess.item); pManager.AddBooleanParameter("Status", "St", "True when the layer has been activated.", GH_ParamAccess.item); }
/// <summary> /// This is the method that actually does the work. /// </summary> /// <param name="DA">The DA object is used to retrieve from inputs and store in outputs.</param> protected override void SolveInstance(IGH_DataAccess DA) { bool active = false; string path = "";
if (!DA.GetData(0, ref active)) return; if (!DA.GetData(1, ref path)) return;
int layer_index = -1; bool status = false;
if (path != null) {
Rhino.RhinoDoc doc = Rhino.RhinoDoc.ActiveDoc; Rhino.DocObjects.Tables.LayerTable layertable = doc.Layers;
layer_index = layertable.FindByFullPath(path, true);
if (layer_index > 0) { // if exists RhinoDoc.ActiveDoc.Layers.SetCurrentLayerIndex(layer_index, true); status = true; } }
DA.SetData(0, layer_index); DA.SetData(1, status); }
Now originally I was getting exceptions when changing multiple layers' visibility properties, which would cause the Event Listener to fire and try to read the Visibility property before the memory has been released by the Set Layer Visibility component. That led me to add an "Exceptions" input, that would allow me to disable the reading of Visibility events at the source in the Layer Events listener. That helped me manage about 95% of the crashes I was getting, but I still get strange crashes in other event properties, even when that property shouldn't be affected. For instance, I am getting a crash here on the Name property in the event from the delegate function, even though I am only changing Visibility at any one time:
I have a few ideas but they all seem pretty hacky. One is to try to set a flag that is readable by any component in the plugin -- so that the event listener can see if a "set" component is currently running and abort before causing an exception. The other is creating a delay in the event listener, somthing like 200ms, to allow any set components to finish what they are doing before reading the event. Neither seems super ideal.
Any ideas?
Thanks,
Marc
…
I wanted to use it for a client, really I can't since they will freak out about a weird version of Rhino being needed.
http://discourse.mcneel.com/t/scripting-blendsrf/24635
http://mcneel.myjetbrains.com/youtrack/issue/RH-29978
What you call trivial is the core of your business, the core of your product, meaning Grasshopper user ability to access serious commands or not. This is, after all, one of the most important commands in the entire Rhino universe. Without it, I have to just completely abandon NURBS and edit meshes since I can't join surfaces smoothly so I have to stop using fragments at all and only meshes afford local detail well compared to single NURBS surfaces. Only polysurfaces can mix in little high UV count blends to deal with tight local detail.
I guess I'll switch to the WIP now. Test that, and just tell clients, hey, that's life. It's not exactly easy to find the WIP download, being a hidden "Serengeti" topic on the main Rhino forum, but I can offer the membership link.
http://discourse.mcneel.com/t/how-do-i-actually-download-serengeti/23846
http://www.rhino3d.com/download/rhino/wip
I had to manually install IronPython 2.7.5 too, to fix a broken Python system:
http://ironpython.codeplex.com/releases/view/169382
Now, where on Earth do I find the Rhinocommon manual for Rhino 6 WIP?
I guess it's within the main Rhino EditPythonScript editor, though that can't be searched like a normal manual:
CreateBlendSurface(face0: BrepFace, edge0: BrepEdge, domain0: Interval, rev0: bool, continuity0: BlendContinuity, face1: BrepFace, edge1: BrepEdge, domain1: Interval, rev1: bool, continuity1: BlendContinuity) -> Array[Brep]
Makes a surface blend between two surface edges.
face0: First face to blend from. edge0: First edge to blend from. domain0: The domain of edge0 to use. rev0: If false, edge0 will be used in its natural direction. If true, edge0 will be used in the reversed direction.
continuity0: Continuity for the blend at the start. face1: Second face to blend from. edge1: Second edge to blend from. domain1: The domain of edge1 to use. rev1: If false, edge1 will be used in its natural direction. If true, edge1 will be used in the reversed direction.
continuity1: Continuity for the blend at the start. Returns: Array of Breps if successful.
Now I have normal, productive homework, of figuring out how to specify edges from a Python script.
I'll just sell this extra special capability of Rhino 5 WIP from Grasshopper as a cutting edge advanced new feature other lowly consultants can't match, assuming I can get it to work first.
The initial strategy is to Grasshopper create discrete surfaces, blow holes in a parent surface, scale down and move the little surfaces away, and just blend everything together into a polysurface. Then a client won't freak out so badly when I show them how to use meshes instead, since at least there's an alternative straight from NURBS, that maybe isn't as creatively open ended, but will get them out of a bind if their own client freaks out about meshes converted to NURBS via ZBrush ZRemesher run through T-Splines to get a smooth NURBS polysurface surface that looks like odd patchwork.
Alas, the above Rhinocommon blurb is incomplete, lacking info about what values for continuity are defined as, such as position, tangency, or curvature. I guess I'll just use try numbers.
…
curve or locus] of a segment AB, in English. The set of all the points from which a segment, AB, is seen under a fixed given angle.
When you construct l'arc capable —by using compass— you obviously need to find the centre of this arc. This can be easily done in GH in many ways by using some trigonometry (e.g. see previous —great— solutions). Whole circles instead of arcs provide supplementary isoptics —β-isoptic and (180º-β)-isoptic—. Coherent normals let you work in any plane.
Or you could just construct β-isoptics of AB by using tangent at A (or B). I mean [Arc SED] component.
If you want the true β-isoptic —the set of all the points— you should use {+β, -β} degrees (2 sides; 2 solutions; 2 arcs), but slider in [-180, +180] degrees provides full range of signed solutions. Orthoptic is provided by ±90º. Notice that ±180º isoptic is just AB segment itself, and 0º isoptic should be the segment outside AB —(-∞, A] U [B, +∞)—. [Radians] component is avoidable.
More compact versions can be achieved by using [F3] component. You can choose among different expressions the one you like the most as long as performs counter clockwise rotation of vector AB, by 180-β degrees, around A; or equivalent. [Panel] is totally avoidable.
Solutions in XY plane —projection; z = 0—, no matter A or B, are easy too. Just be sure about the curve you want to find the intersection with —Curve; your wall— being contained in XY plane.
A few self-explanatory examples showing features.
1 & 5 1st ver. (Supplementary isoptics) (ArcCapableTrigNormals_def_Bel.png)
2 & 6 2nd ver. (SED) (ArcCapableSED_def_Bel.png)
3 & 7 3rd ver. (SED + F3) (ArcCapableSEDF3_def_Bel.png)
4 & 8 4th ver. (SED + F3, Projection) (ArcCapableSEDProjInt_def_Bel.png)
If you want to be compact, 7 could be your best choice. If you prefer orientation robustness, 5. Etcetera.
I hope these versions will help you to compact/visualize; let me know any feedback.
Calculate where 2 points [A & B] meet at a specific angle is just find the geometrical locus called arco capaz in Spanish, arc capable in French (l'isoptique d'un segment de droite) or isoptic [curve or locus]
of a segment AB, in English. The set of all the points from which a segment,
AB, is seen under a fixed given angle.…
peuvent se diviser une surface avec ne importe quel motif imaginable. 3. Ici, je fournir un moyen de le faire via Lunchbox ... cela fonctionne mais il est fixe et donc nous avons besoin de jouer avec des arbres de données afin de créer le motif approprié par cas. 4. L'autre composante est un joint C # qui fait beaucoup de choses autres que de diviser ne importe quelle collection de points avec de nombreux modèles (voir le modèle ANDRE que je ai fait pour vous). 5. Vous devez décomposer une polysurface en morceaux afin de travailler sur les subdivisions. 6. Je donne une autre définition ainsi que pourrait agir comme un tutoriel sur la façon de traiter des ensembles de points via des composants de GH standards et des méthodes classiques.
Avertissez si tous ceux-ci apparaissent floue pour vous: Si oui, je pourrais écrire une définition utilisant des composants de GH classiques - mais vous perdrez les variations de motifs de division.
mieux, Peter
…
ers can be applied from the right click Context Menu of either a component's input or output parameters. With the exception of <Principal> and <Degrees> they work exactly like their corresponding Grasshopper Component. When a I/O Modifier is applied to a parameter a visual Tag (icon) is displayed. If you hover over a Tag a tool tip will be displayed showing what it is and what it does.
The full list of these Tags:
1) Principal
An input with the Principal Icon is designated the principal input of a component for the purposes of path assignment.
For example:
2) Reverse
The Reverse I/O Modifier will reverse the order of a list (or lists in a multiple path structure)
3) Flatten
The Flatten I/O Modifier will reduce a multi-path tree down to a single list on the {0} path
4) Graft
The Graft I/O Modifier will create a new branch for each individual item in a list (or lists)
5) Simplify
The Simplify I/O Modifier will remove the overlap shared amongst all branches. [Note that a single branch does not share any overlap with anything else.]
6) Degrees
The Degrees Input Modifier indicates that the numbers received are actually measured in Degrees rather than Radians. Think of it more like a preference setting for each angle input on a Grasshopper Component that state you prefer to work in Degrees. There is no Output option as this is only available on Angle Inputs.
7) Expression
The Expression I/O Modifier allows you change the input value by evaluating an expression such as -x/2 which will have the input and make it negative. If you hover over the Tag a tool tip will be displayed with the expression. Since the release of GH version 0.9.0068 all I/O Expression Modifiers use "x" instead of the nickname of the parameter.
8) Reparameterize
The Reparameterize I/O Modifier will only work on lines, curves and surfaces forcing the domains of all geometry to the [0.0 to 1.0] range.
9) Invert
The Invert Input Modifier works in a similar way to a Not Gate in Boolean Logic negating the input. A good example of when to use this is on [Cull Pattern] where you wish to invert the logic to get the opposite results. There is no Output option as this is only available on Boolean Inputs.
…
ing the maps to the broader community.
At the moment, there are just a few known issues left that I have to fix for complex geometric cases but they should run smoothly for most energy models that you generate with Honeybee. Within the next month, I will be clearing up these last issues and, by the end of the month, there will be an updated youtube tutorial playlist on the comfort tools and how to use them.
In the meantime, there's an updated example file (http://hydrashare.github.io/hydra/viewer?owner=chriswmackey&fork=hydra_2&id=Indoor_Microclimate_Map) and I wanted to get you all excited with some images and animations coming out of the design part of my thesis. I also wanted to post some documentation of all of the previous research that has made these climate maps possible and give out some much deserved thanks. To begin, this image gives you a sense of how the thermal maps are made by integrating several streams of data for EnergyPlus:
(https://drive.google.com/file/d/0Bz2PwDvkjovJaTMtWDRHMExvLUk/view?usp=sharing)
To get you excited, this youtube playlist has a whole bunch of time-lapse thermal animations that a lot of you should enjoy:
https://www.youtube.com/playlist?list=PLruLh1AdY-Sj3ehUTSfKa1IHPSiuJU52A
To give a brief summary of what you are looking at in the playlist, there are two proposed designs for completely passive co-habitation spaces in New York and Los Angeles.
These diagrams explain the Los Angeles design:
(https://drive.google.com/file/d/0Bz2PwDvkjovJM0JkM0tLZ1kxUmc/view?usp=sharing)
And this video gives you and idea of how it thermally performs:
These diagrams explain the New York design:
(https://drive.google.com/file/d/0Bz2PwDvkjovJS1BZVVZiTWF4MXM/view?usp=sharing)
And this video shows you the thermal performance:
Now to credit all of the awesome people that have made the creation of these thermal maps possible:
1) As any HB user knows, the open source engines and libraries under the hood of HB are EnergyPlus and OpenStudio and the incredible thermal richness of these maps would not have been possible without these DoE teams creating such a robust modeler so a big credit is definitely due to them.
2) Many of the initial ideas for these thermal maps come from an MIT Masters thesis that was completed a few years ago by Amanda Webb called "cMap". Even though these cMaps were only taking into account surface temperature from E+, it was the viewing of her radiant temperature maps that initially touched-off the series of events that led to my thesis so a great credit is due to her. You can find her thesis here (http://dspace.mit.edu/handle/1721.1/72870).
3) Since the thesis of A. Webb, there were two key developments that made the high resolution of the current maps believable as a good approximation of the actual thermal environment of a building. The first is a PhD thesis by Alejandra Menchaca (also conducted here at MIT) that developed a computationally fast way of estimating sub-zone air temperature stratification. The method, which works simply by weighing the heat gain in a room against the incoming airflow was validated by many CFD simulations over the course of Alejandra's thesis. You can find here final thesis document here (http://dspace.mit.edu/handle/1721.1/74907).
4) The other main development since the A. Webb thesis that made the radiant map much more accurate is a fast means of estimating the radiant temperature increase felt by an occupant sitting in the sun. This method was developed by some awesome scientists at the UC Berkeley Center for the Built Environment (CBE) Including Tyler Hoyt, who has been particularly helpful to me by supporting the CBE's Github page. The original paper on this fast means of estimating the solar temperature delta can be found here (http://escholarship.org/uc/item/89m1h2dg) although they should have an official publication in a journal soon.
5) The ASHRAE comfort models under the hood of LB+HB all are derived from the javascript of the CBE comfort tool (http://smap.cbe.berkeley.edu/comforttool). A huge chunk of credit definitely goes to this group and I encourage any other researchers who are getting deep into comfort to check the code resources on their github page (https://github.com/CenterForTheBuiltEnvironment/comfort_tool).
6) And, last but not least, a huge share of credit is due to Mostapha and all members of the LB+HB community. It is because of resources and help that Mostapha initially gave me that I learned how to code in the first place and the knowledge of a community that would use the things that I developed was, by fa,r the biggest motivation throughout this thesis and all of my LB efforts.
Thank you all and stay awesome,
-Chris…
ssibili e facili da usare. Il corso parte dalle basi della programmazione di arduino fino ad arrivare all’interazione tra un oggetto fisico ed un imput informativo. tutor: Gianpiero Picerno Ceraso
Programma: I giorno Introduzione al Phisical Computing, input digitali e analogici, le basi del linguaggio di programmazione, esempi applicativi; led, pulsanti, fotorestistenze, servo motore, sensore di temperatura, di flessione, sensori di movimento, potenziometri.
II giorno Arduino ethernet, uso di un relè per carichi elevati, accelerometro, introduzione a Processing, interazione di Arduino e Processing, Introduzione a Grassoppher e Firefly e interazione con Arduino.
orario corso: 10:00 – 13:00 e 14:00 – 17:00 (pausa pranzo 13:00 – 14:00) costo: 150€ + IVA deadline: 13 marzo numero minimo di partecipanti: 3
Per iscrizioni scrivi a info@medaarch.com specificando nome, cognome, mail, recapito telefonico e il nome del corso al quali sei interessato. In seguito all’invio del modulo di pre-iscrizione, i partecipanti riceveranno una mail contenente tutte le specifiche di pagamento.
Per seguire il cluster su Arduino è necessario installare il software Arduino 1.0.5 al seguente linkhttp://arduino.cc/en/Main/Software#.Ux3hQj95MYE facendo attenzione a scaricare quello relativo al proprio sistema operativo, Windows 32 o 64 e Mac OS.
Software necessari solo per una parte del corso: Processing 2.1.1 https://processing.org/download/?processing
Rhino 5 http://www.rhino3d.com/it/download Grasshopper for Rhino5http://www.grasshopper3d.com/page/download-1Firefly http://fireflyexperiments.com/
Il cluster rientra in un fitto calendario di attività formative organizzate dalla Medaarch per lanno 2013-2014.…
as the design table? I think this could be 'drawn' and constrained in Inventor in a lot less time. I know the GH model would have a lot of flexibility, but in this case, what can you do with it that wasn't provided by an Inventor model?
Only the 27 lines mentioned were modeled in Rhino, the rest is modeled with GH.
The 5 hrs involved thinking about the approach, defining vertical lines, tilts, elevations, pitch of the roof, intersections.
Once I had decided what my approach would be, and tested the logic with those first lines, points and data path arrangements, it only took one more hour to get to this:
Which is actually quite fast, compared to MCAD workflows.
If you already have components (columns, beams, etc.) modeled and ready to drop into a project, of course it is lightning fast to model simple projects like this example.
I am not as much interested in those situations, because improving efficiency is straightforward and obvious.
I'm more interested in situations where there are no pre-defined families of objects, in which case you need to start from scratch.
The GH model I'm showing is modeled from scratch, except for the 27 lines in Rhino.
Here's one obvious advantage to modeling with GH, once the definition is set-up, it's virtually effortless to change inputs and alter the overall design. Here's an example, lets say we wanted to extend the roof 3 more units, curling away from the original direction.
Plan view before:
And after:
An MCAD app will also allow you to do this, as long as the location of additional elements follows the existing geometric method of definition. What happens if you want completely change the way you locate columns, roof slope, intersection points?
In MCAD, you'll need to re-model the underlying geometry, which will take the same effort as the first round. In GH, this process is not only much faster, it's open to algorithmic approaches, galapagos, etc. and it just takes some simple re-wiring to have all down-stream elements associate themselves to this new geoemtric definition.
For instance, here's the same definition applied to two curves, which are divided in GH, the resulting points are used as a starting point for lines directed at normal from curves.
This is not so easy to do in MCAD.…
Added by Santiago Diaz at 7:55pm on February 24, 2011
occur more than once in the same list, and different elements with identical values can occur more than once. Also, a list may contain lack of elements, referred to as "nulls".
Sets. Strictly speaking a Set is a mathematical construct which adheres to a strict collection of rules and limitations. Basically, a Set is the same as a List, with the exception that it cannot contain the same element more than once, or indeed two or more different elements with the same values. You see, in mathematics there is no difference between a value and an instance of that value, they are the same thing. In programming however it is possible to store the number 7 in more than one spot in the RAM. Grasshopper does not enforce this rule very strongly though, you can use a lot of Set components on lists that have multiple occurrences of the same value. The big difference between Lists and Sets in Grasshopper is that Sets are only defined for simple data types that have trivial equality comparisons. Basically: booleans, integers, numbers, complex numbers, strings, points, vectors, colours and intervals. Lists can contain all kinds of data.
Strings. Strings are text. There's nothing more to it. I don't know why early programmers chose to call them strings, but I suppose it's a better description of the memory representation of them. Strings are essentially sequences of individual characters.
Trees. Trees are the way all data is stored in Grasshopper. Even when you only have a single item, it will still be stored in a tree. A tree is a sorted collection of lists, where each list is identified by a path. A specific path can only occur once in a tree, when you merge two trees together, lists with identical paths are appended to each other. Trees are an attempt to losslessly represent not just the data itself, but also the history of that data. Imagine you have 4 curves {A,B,C,D} and you divide each into 3 points {X,Y,Z}. Then, for each of those points you create a new line segment {X',Y',Z'} and then divide each of those line segments again into 5 points each {K,L,M,N,O}. The way data is stored in trees, it should be possible to figure out whether a point M belongs to X' or to Z', and whether that X' or Z' came from A, B, C or D. This is why paths are often quite long after a while, because they encode a lot of history.
Paths. A Path is nothing more than a list of integers. It's denoted using curly brackets and semi-colons: {A;B;...;Z}. A Path should never be empty {} or have negative integers {0;-1}, but it is certainly possible to create a path like this and it probably won't even crash Grasshopper. Paths are 'grown' by components that (potentially) create more than one output value for a single input value. For example Divide Curve. It creates N points for every single input curve. In cases like this a new integer is appended to the end of the path.
In the next release the Path logic in Grasshopper is somewhat different. I fixed a number of obscure bugs (hopefully without introducing new fresh bugs) and special cased certain operations to somewhat reduce the speed at which paths grow. This may well break files that rely on a specific tree layout, but I hope the temporary sacrifice will be worth the long-term benefits.
--
David Rutten
david@mcneel.com
Poprad, Slovakia…